Enzymic peeling of Indian grapefruit (Citrus paradisi)

The tough nature of grapefruit (Citrus paradisi) peel and its close adherence to the inner fruit sections limit the industrial processing of grapefruit. Two commercial peeling enzymes coded as ‘Brand A’ and ‘Brand B’ were studied for enzymic peeling of Indian grapefruit by vacuum infusion. The peeling process was optimised with respect to process parameters such as scalding time, enzyme concentration, vacuum infusion time and incubation time. © 2001 Society of Chemical Industry     

Enzymic debittering of Indian grapefruit (Citrus paradisi) juice

The present work explores the use of enzymes for debittering grapefruit (Citrus paradisi) juice. The debittering process was optimised using a statistical approach. A full factorial design using enzyme concentration (0.25, 0.5 and 1.0 g l^?1), incubation temperature (25, 30 and 40 °C) and time of incubation (1, 2 and 4 h) as variables gave a regression equation that could predict the extent of debittering. The optimum set of conditions recommended is an enzyme concentration of 1 g l^?1 at 40 °C for 4 h. The extent of naringin breakdown achieved under these conditions was 75%. © 2002 Society of Chemical Industry     

Variation in Furanocoumarin Content and New Furanocoumarin Dimers in Commercial Grapefruit (Citrus paradisi Macf.) Juices

ABSTRACT: Grapefruit ( Citrus paradisi Macf.) sales and crop value have declined during the last decade. One reason is consumer concerns about possible drug interactions. Coadministered grapefruit increases the bioavailability of some medicines because it contains furanocoumarins that inhibit an intestinal enzyme (cytochrome P450-3A4 or CYP3A4) that normally metabolizes these drugs. Only drugs metabolized by intestinal CYP3A4 are significantly affected when taken with grapefruit juice, but the magnitude of the effect varies considerably between studies, indicating that there are differences in the amount of components responsible for CYP3A4 inhibition in commercial grapefruit juices. Content variation of 6,7-dihydroxybergamottin, bergamottin, and 6 furanocoumarin dimers were determined for 58 commercial grapefruit juices collected over 2 seasons. The content of 6,7-dihydroxybergamottin ranged from 0.2 to 7.7 ppm in all juices tested, and averaged 1.8 ± 0.85 ppm in the red compared with 2.9 ± 2.07 ppm for white grapefruit juices. Bergamottin content ranged from 1.6 to 7.3 ppm for all juices and averaged 3.4 ± 0.98 and 4.2 ± 1.23 ppm and in red and white grapefruit juices, respectively. Only 1 dimer varied significantly between the red and white juice types. Dihydroxybergamottin and 2 dimer compounds were significantly lower in shelf-stable or nonrefrigerated products compared with refrigerated products whereas bergamottin and 1 dimer compound occurred at higher levels in the shelf-stable products. Individual measured dimer compounds varied up to 60-fold in all juices, but the sum of all 6 dimers varied only 14-fold. The clinical significance in terms of CYP3A4 inhibition is uncertain. The presence of 3 new furanocoumarin dimers are also reported.     

Distribution of bound and free phenolic acids in oranges (Citrus sinensis) and Grapefruits (Citrus paradisi)

Free phenolic acids may be the precursors for vinyl phenols and off-flavours formed in citrus products during storage. Quantitative determination of free and bound phenolic acids in fruit parts of grapefruit (Citrus paradisi Macfadyen) and oranges (Citrus sinensis (L) Osbeck) was performed by extraction with ethyl acetate, silica gel column chromatography and HPLC analyses of samples before and after alkaline hydrolysis. The content of free and bound phenolic acids was further determined in juice derived from fruit harvested early, mid and late in season. As found previously for ferulic acid, phenolic acids occur mainly in bound forms in grapefruits and oranges. In both fruits the peels contained the major portion of cinnamic acids compared with the endocarp, and the flavedo was richer in hydroxycinnamic acids than the albedo. In most cases, hydroxycinnamic acid content was in the following order: ferulic acid>sinapic acid>coumaric acid>caffeic acid. Results showed that the content of bound cinnamic acids was unchanged or slightly elevated from early to late season. However, the content of free acids was reduced during that period.     

A review of limonin in grapefruit (Citrus paradisi) juice,its relationship to flavour,and efforts to reduce it

Ever since limonin was first discovered in grapefruit (Citrus paradisi Macf) juice in 1965 and found responsible for significantly contributing to bitterness in the juice, a great deal of research has been directed towards understanding its role therein. Information is presented relative to limonin's chemical determination, taste threshold and content in grapefruit juice, and to relevant legislation. Also considered are (1) several factors affecting the limonin content of grapefruit juice (2) the effect of limonin content on sensory flavour in grapefruit juice (3) the interaction between the Brix: acid ratio and limonin content in affecting grapefruit juice flavour and (4) methods for reducing limonin in citrus juices generally. Finally, recommendations for future studies on limonin in grapefruit juice are reviewed.     

响应面法优化柑橘皮柠檬苦素提取工艺

为优化柑橘皮中柠檬苦素的提取工艺,在单因素试验基础上,采用响应面分析法研究了提取时间、提取温度和液料比对柑橘皮柠檬苦素得率的影响,建立具有良好预测性能的数学模型,通过响应面分析法确定柑橘皮中柠檬苦素最优提取工艺条件。试验结果表明,提取温度和液料比对柑橘皮柠檬苦素得率的影响显著,最优提取条件为:提取时间20h,提取温度为51.5℃和液料比为96∶3(mL/g)。     

陈窖豆豉粑传统工艺剖析及优势菌群鉴定

工艺独特的贵州黔西、大方两地陈窖豆豉粑微生物区系分离鉴定结果表明,黔西陈窖豆豉粑以泛酸芽胞杆菌(B.pantothenticus)、蜂房芽胞杆菌(B.alvei)、坚强芽胞杆菌(B.firmus)等芽胞杆菌为优势菌群,为细菌发酵型产品,而大方陈窖豆豉粑则是爪哇毛霉(M.javanicusWehmer)、鲁氏毛霉(M.rouxians(Calmette)Wehmer)、总状毛霉(M.racemosusFres.)、坚强芽胞杆菌、革兰氏阳性无芽胞杆菌等霉菌和细菌共存发酵的复合发酵型产品,同时两地产品的后期陈窖阶段,均有球菌(Stophylococcus或Pediococcus)和酵母菌(HansenulaanomalaH.etp.sydowvar.amomala)富集,可能对产品的风味和营养起着一定作用。     

数字图像处理技术结合偏最小二乘法定量分析柑橘质量

目的：构建柑橘质量模型,实现其计算机视觉法质量检测与在线分级。方法：以湖南湘中成熟中期涟红温州蜜柑为研究对象,对计算机视觉系统采集的各柑橘的4 幅图像进行图像裁切、图像去背景、图像二值化与取反操作后,提取柑橘区域像素,以柑橘区域像素与图像像素比为自变量,建立柑橘质量偏最小二乘回归(PLS)预测模型。结果：柑橘质量预测绝对误差为－ 14.9092～4.9981g,平均误差为－ 3.9278g,误差标准差4.5210g,± 10g 质量内的正确识别率为93.3333%,± 8g 质量内正确识别率76.6667%。结论：通过计算机视觉技术进行柑橘质量在线分级和生长期中挂果质量的监测是可行的。     

Inhibition of LDL Oxidation by Red Orange (Citrus sinensis) Extract and its Active Components

ABSTRACT: Oxidative modification of low-density lipoprotein (LDL) appears to play a pivotal role in atherosclerosis. In the present study the effect of several concentrations of rutin, its aglycon quercetin, cyanidin 3- O -β-d-glucoside, its aglycon cyanidin, hydroxycinnamic acids, and a standardized red orange ( Citrus sinensis varieties) extract (ROE) on LDL oxidation was tested. Lipid peroxidation was monitored by conjugated diene formation and by different electrophoretic mobility of native LDL and oxidized LDL. Results obtained in the present study suggest specific effects of flavonoids tested and, in particular, of ROE on the prevention of LDL oxidation involved in the development of cardiovascular diseases.     

热水提取胡柚果皮中矿物质、酚类物质及其水提液抗氧化性研究

目的:研究热水提取胡柚果皮矿物质、酚类物质的效率及其提取液的抗氧化能力。方法:原子吸收光谱法测定七种主要矿物质;高效液相法测定胡柚皮中七种主要酚酸和六种黄酮;福林酚法、FRAP、DPPH法测定提取液的抗氧化能力。结果:热水提取可以有效提取胡柚果皮中的酚类物质与部分矿物质。抗氧化能力分析表明,热水提取液具有与甲醇提取液相近的抗氧化能力。结论:传统中药煎煮条件(100℃,30min)可以有效提取柑橘类中药的酚类物质与部分矿物质。      

牛奶乳饼加工工艺优化及其营养成分分析

以贯筋藤蛋白酶、新鲜荷斯坦牛奶等为原料,通过单因素筛选和响应面试验优化凝乳剂配方、凝乳工艺,研究优化工艺乳饼的产品质量。结果表明,新型凝乳剂的最佳配方为贯筋藤蛋白酶液(蛋白酶质量分数0.15%)添加量17.95%,柠檬酸添加量0.023 3%,氯化钙添加量0.009 85%;最佳凝乳温度为83.25℃。优化工艺乳饼感官评分为(85.7±1.32)分,高于传统酸水工艺(P0.05);水分、粗蛋白、粗脂肪含量分别为(52.94±1.03)%、(20.09±0.57)%、(22.54±0.48)%,灰分、钙、磷含量较传统酸水工艺提高(P0.05);游离氨基酸、游离脂肪酸总量分别为(77.64±5.80)、(1 953.76±53.53)mg/100 g;维生素含量丰富,脂溶性VA、VE含量提高(P0.05)。2种工艺加工乳饼微观结构存在差异,传统酸水乳饼呈现片状或团状结构,优化工艺乳饼呈现三维网状结构。优化工艺乳饼色泽鲜亮、质地均匀,具有乳饼特有的滋气味和植物清香,较传统酸水工艺产品质量进一步提高,是一种风味独特的高营养产品。     

纤维素酶提取湘西椪柑皮中总黄酮的工艺优化研究

采用响应面法对纤维素酶提取椪柑皮中总黄酮的工艺进行优化。结果表明,酶法提取椪柑皮总黄酮的最佳工艺条件为酶用量120U/mL、酶解温度52℃、酶解时间140min、酶解pH4.35,总黄酮得率可达1.85%。     

香橼精油的组成及香气活性成分的GC-MS-O分析

采用水蒸气蒸馏法提取香橼皮精油,运用气相色谱-质谱-嗅辨仪联机技术(GC-MS-O)对其成分组成及香气活性成分进行了研究。结果显示:香橼精油中柠檬烯的含量最高,为精油的50.53%,其次为对伞花烃(16.40%),其他含量较高的成分还有γ-萜品烯(8.70%)、罗勒烯(5.03%)、β-蒎烯(3.35%),α-蒎烯(2.66%)和β-月桂烯(2.30%)。另外,检测出11种香气活性成分,其中已鉴定的9种为α-蒎烯、β-蒎烯、对伞花烃、柠檬烯氧化物、里那醇、4-萜品醇、反-对-薄荷-2,8-二烯醇、丙酸松油酯、乙酸橙花酯、巴伦西亚橘烯。嗅闻结果显示,伞花烃和丙酸松油酯可能对香橼的特征香气起重要作用。     

AB-8大孔吸附树脂精制芦柑皮总黄酮及黄酮类化合物的分离

目的：研究AB-8大孔吸附树脂精制芦柑皮总黄酮的工艺条件及芦柑皮黄酮类化合物的分离纯化。方法：采用AB-8大孔吸附树脂动态法精制芦柑皮总黄酮,考察上样液总黄酮质量浓度、pH值、上样流速、洗脱液乙醇体积分数对吸附解吸性能的影响;然后将精制的芦柑皮总黄酮经硅胶柱层析、半制备高效液相等技术进行分离纯化,并根据理化性质和波谱数据鉴定化学结构。结果：AB-8大孔树脂精制芦柑皮总黄酮的最佳工艺条件为上样液总黄酮质量浓度3.03 mg/mL、上样液pH 3.0、上样流速3.0 BV/h、洗脱液乙醇体积分数为90%,最优条件下可使芦柑皮总黄酮的纯度从17.8%提高到63.1%;此外,从精制的芦柑皮黄酮中分离到8 个黄酮类化合物,分别鉴定为：橘皮素、川陈皮素、4’,5,7,8-四甲氧基黄酮、5-去甲基-橘皮素、橙黄酮、橙浸膏、柚皮苷、橙皮苷。结论：AB-8大孔树脂能很好地富集纯化芦柑皮总黄酮,该法简单、可行;从精制的芦柑皮黄酮中分离到8 个黄酮类化合物,其中,4’,5,7,8-四甲氧基黄酮、5-去甲基-橘皮素、橙浸膏、柚皮苷、橙皮苷首次从芦柑皮中分得。     

Product Yield and Gaping in Cold-smoked Atlantic Salmon (Salmo salar) Fillets as Influenced by Different Injection-salting Techniques

Product yield and fillet gaping severity were determined in cold‐smoked Atlantic salmon fillets subjected to injection‐salting. Effects of process parameter settings (brine injection pressure, number of repeated injections, needle speed, injection of brine in 1 or 2 directions, and chilled fillet resting before smoking) were tested. Repeated injections increased the yield up to 5.3% (wt/wt). Increasing injection pressure significantly increased the severity of fillet gaping in smoked fillets by 18%. Brine injection directions or needle speed did not affect smoking yield. The stability of the injection system was high. The results show that choice of process parameter settings during injection‐salting affects product yield after smoking.     

基于SPME-GC-O-MS的清真酱牛肉加工过程中挥发性风味成分变化分析

以清真酱牛肉为研究对象,分析加工过程中挥发性风味物质的变化规律。利用固相微萃取-气相色谱-质谱联用结合嗅闻技术,分别对预煮、煮制1 h、煮制完成和浸泡冷却后的酱牛肉样品4 个阶段的挥发性风味物质进行定性定量分析。结果表明,清真酱牛肉加工过程中共鉴定出103 种挥发性风味物质,4 个阶段样品的挥发性风味物质种类数量分别为46、51、58 种和54 种,4 个阶段共有的风味化合物为18 种;加工过程中醛类、醚类、含氮含硫及杂环化合物相对含量呈增加趋势,酯类物质相对含量随加热逐渐下降,醇类、酮类和酸类物质相对含量无明显变化。     

A Gompertz Model Approach to Microbial Inactivation Kinetics by High‐Pressure Processing (HPP): Model Selection and Experimental Validation

A recently proposed Gompertz model (GMPZ) approach describing microbial inactivation kinetics by high‐pressure processing (HPP) incorporated the initial microbial load (N₀) and lower microbial quantification limit (N_lim), and simplified the dynamic effects of come‐up time (CUT). The inactivation of Listeria innocua in milk by HPP treatments at 300, 400, 500, and 600 MPa and pressure holding times (t_hold) ≤10 min was determined experimentally to validate this model approach. Models based on exponential, logistic‐exponential, and inverse functions were evaluated to describe the effect of pressure on the lag time (λ) and maximum inactivation rate (μ_max), whereas the asymptote difference (A) was fixed as A = log₁₀(N₀/N_lim). Model performance was statistically evaluated and further validated with additional data obtained at 450 and 550 MPa. All GMPZ models adequately fitted L. innocua data according to the coefficient of determination (R² ≥ 0.95) but those including a logistic‐exponential function for μ_max(P) were superior (R² ≥ 0.97). These GMPZ versions predicted that approximately 597 MPa is the theoretical pressure level (P_λ) at which microbial inactivation begins during CUT, mathematically defined as λ (P = P_λ) = t_CUT, and matching the value observed on the microbial survival curve at 600 MPa. As pressure increased, predictions tended to slightly underestimate the HPP lethality in the tail section of the survival curve. This may be overseen in practice since the observed microbial counts were below the predicted log₁₀ N values. Overall, the modeling approach is promising, justifying further validation work for other microorganisms and food systems.